Dreadnought Assembly Questions

stogie · April 2014

I am in the process of building my first dreadnought (AL Y236906 and Neutrik NL4's) and had a of couple of questions. I have read that the wiring should be as follows:

Red/Yellow (right pin) to 1+
Black/Orange (right blade) to 1-
Grey/Brown (left pin) to 1+
Blue/Violet (left blade) to 1-

Does this mean that once assembled the right speaker has to hooked up to the Neutrik plug with the red/yellow and black/orange combination and the left speaker has to be hooked up the Neutrik plug with the grey/brown and blue/violet combo? I wouldn't think it would be directional like that but I'm just learning this stuff.

Also, is the transformer just mounted by drilling a hole through the bottom of the dynamatted aluminum box, then mounted using the supplied mounting pads and hardware? Or is there something else that should be between the transformer and the bottom? Thanks

F1nut · April 2014

Does this mean that once assembled the right speaker has to hooked up to the Neutrik plug with the red/yellow and black/orange combination and the left speaker has to be hooked up the Neutrik plug with the grey/brown and blue/violet combo?

Yes.

Also, is the transformer just mounted by drilling a hole through the bottom of the dynamatted aluminum box, then mounted using the supplied mounting pads and hardware? Or is there something else that should be between the transformer and the bottom?

Basically yes, but I would suggest using non-ferrous hardware such as stainless steel or brass.

westmassguy · April 2014

Jesse, can you elaborate on the reason for dedicated left and right?

On3s&Z3r0s · April 2014

So, what are the downsides to hooking the Dreadnaught up backwards and using a non-ferrous enclosure or hardware? I've been running an AL-based Dreadnaught for well over a year and didn't know to pay attention to which set of posts each speaker was hooked to. (I'll definitely take a close look at that now.) But either I just got lucky and hooked it up right by accident, or I can't hear much difference due to having hooked it up wrong. I haven't switched the connections on the Dreadnaught, but I do go back and forth between the Dreadnaught and a direct connection between the speakers occasionally, and both sound nearly identical.

Also, I'm using a steel enclosure that is plenty ferrous... magnets stick to it great. Is there some reason for having only non-magnetic stuff around the transformer?

Schurkey · April 2014

As long as the primary transformer windings go to one speaker, and the secondary transformer windings go to the other speaker, left and right aren't critical. You do need to keep the color codes paired-up, and pay attention to + and - .

These transformers are NOT symmetrical, so the primary and secondary windings aren't identical. Theoretically, this should result in somewhat greater SDA volume in one channel, and somewhat less SDA volume in the other...but DK and others don't seem to be bothered by this asymmetry. I haven't put my Dreadnought together yet, and for that matter I'd have to buy different speakers to use it at all--so I can't give you any experienced-based wisdom regarding the transformer windings.

Magnetic hardware has the potential to change the specs of the transformer. Non-magnetic (which is almost but not quite the same as non-ferrous) won't screw with the magnetic force of the transformer. Stainless hardware is (USUALLY) non- or slightly-magnetic, but it's still ferrous.

stogie · April 2014

I assume that the bolt, nut, washer and metal dish that AL shipped with the transformer are non-ferrous, but I will check with them just to be sure. They also sent a metal sleeve/shield to encircle the transformer. I just have to secure it in some fashion- zip ties or duct tape or something. If the right and left connections are critical then I'll have to identify L & R on the box somehow.

On3s&Z3r0s · April 2014

Schurkey wrote: »

As long as the primary transformer windings go to one speaker, and the secondary transformer windings go to the other speaker, left and right aren't critical. You do need to keep the color codes paired-up, and pay attention to + and - .

These transformers are NOT symmetrical, so the primary and secondary windings aren't identical. Theoretically, this should result in somewhat greater SDA volume in one channel, and somewhat less SDA volume in the other...but DK and others don't seem to be bothered by this asymmetry. I haven't put my Dreadnought together yet, and for that matter I'd have to buy different speakers to use it at all--so I can't give you any experienced-based wisdom regarding the transformer windings.

Magnetic hardware has the potential to change the specs of the transformer. Non-magnetic (which is almost but not quite the same as non-ferrous) won't screw with the magnetic force of the transformer. Stainless hardware is (USUALLY) non- or slightly-magnetic, but it's still ferrous.

When I wired mine up I did pay close attention to the polarity and getting the leads paired correctly. If right vs left just comes down to one SDA side being louder it almost seems like you'd want to swap back and forth to get the best (or at least most innocuous) effect depending on room placement.

I do remember seeing a thread quite a while back discussing aluminum vs steel as an enclosure, but I didn't remember there being a definitive outcome in terms of one being noticeably superior. My transformer didn't come with any special shielding, but the fact that they are now providing shielding seems to suggest AL thinks it could be an issue. At the time I got my enclosure though, it was the same one DK had used for one of his builds, so I figured, good enough for DK, good enough for me.

F1nut · April 2014

Yes correction, I meant non-magnetic....thanks Schurkey.

westmassguy wrote: »

Jesse, can you elaborate on the reason for dedicated left and right?

As stated, the primary windings go to one speaker, the secondary windings go to the other.

To keep it as simple as possible in order not to confuse anyone the following works perfectly and there is no reason to change it.

Red/Yellow (right pin) to 1+
Black/Orange (right blade) to 1-
Grey/Brown (left pin) to 1+
Blue/Violet (left blade) to 1-

stogie, put a magnet to the hardware. If it sticks to any of it you don't want to use it.

F1nut · April 2014

If right vs left just comes down to one SDA side being louder it almost seems like you'd want to swap back and forth to get the best (or at least most innocuous) effect depending on room placement.

No one that I'm aware of has noticed an imbalance.

On3s&Z3r0s · April 2014

Cool, y'all freaked me out with that right/left thing. My A1 is buried in the bottom cabinet of a china hutch between the speakers. I have no idea which speaker is cabled to which set of posts. This saves me half an hour of digging it out and unscrewing two dozen hex screws to find out.

Schurkey · April 2014

On3s&Z3r0s wrote: »

When I wired mine up I did pay close attention to the polarity and getting the leads paired correctly. If right vs left just comes down to one SDA side being louder it almost seems like you'd want to swap back and forth to get the best (or at least most innocuous) effect depending on room placement.

F1nut wrote: »

No one that I'm aware of has noticed an imbalance.

Agreed. I had hoped to goad DK into using his Magic Scope to analyze the electrical imbalance of these "isolation transformers" but he didn't take the bait like I expected.

These transformers are all intended to accept 115 or 230 volts input on the primary windings, and to provide 115 or 230 volts output on the secondary side. Since all transformers have some amount of "loss", the manufacturer compensates by adding some extra winding to the secondary windings, so the losses of the transformer don't show up as reduced voltage on the secondary windings. We Polkies are using the transformers for an entirely different purpose, we're transferring power BOTH directions--from primary to secondary, but also from secondary to primary. Since the transformer isn't symmetrical, what works to prevent voltage loss in one direction makes the voltage loss worse in the other direction. But since I haven't actually built one, and I don't have the Electrical Engineering background (or the 'scope) to run tests, I am just making guesses that the SDA signal is compromised. Yes, nobody who's using one of these is complaining of SDA signal imbalance. Maybe that's good enough.

On3s&Z3r0s wrote: »

I do remember seeing a thread quite a while back discussing aluminum vs steel as an enclosure, but I didn't remember there being a definitive outcome in terms of one being noticeably superior. My transformer didn't come with any special shielding, but the fact that they are now providing shielding seems to suggest AL thinks it could be an issue. At the time I got my enclosure though, it was the same one DK had used for one of his builds, so I figured, good enough for DK, good enough for me.

Aluminum would be preferred over steel--as I understand it--based on electrical conductivity. Better conductivity = better shielding. Copper would be better still, and I suppose that means that silver would be pretty much optimum.

I intended to use copper for my housing until I started pricing copper sheet. Holy crap, has copper pricing gone up.

I have a clever and artistically satisfying aluminum housing, of which I'll post pictures in about ten years when I've actually assembled my Dreadnought into it.

F1nut wrote: »

Red/Yellow (right pin) to 1+
Black/Orange (right blade) to 1-
Grey/Brown (left pin) to 1+
Blue/Violet (left blade) to 1-

I will be building one of these...someday. (I'll have more motivation to build it directly after buying speakers it can be used with.)

I know in my head how it's going to be wired, but just for clarity--please explain the significance of the "1". I get the + and the -, but I don't get the significance of the "1".

F1nut · April 2014

I had hoped to goad DK into using his Magic Scope to analyze the electrical imbalance of these "isolation transformers" but he didn't take the bait like I expected.

LOL

please explain the significance of the "1". I get the + and the -, but I don't get the significance of the "1".

Ah yes, the OP copied that from one of the Dreadnought build threads where SpeakOn connectors were used, hence the "1".

stogie · April 2014

Yes, the 4 pole Neutrick SpeakOn connectors have tabs that are labeled 1+, 1-, 2+, 2-. Of course you only use one pair of the tabs, but the 4 pole version (per their specs) has a wider collar ID (14mm), therefore it will accept a larger gauge wire than the 2 pole version. Which brings me to my next question. Which "reasonably priced" cable/wire is recommended for the interconnect? I have read somewhere that DK used Monster Z3 (I believe) in one of his builds, but I can't find that available anywhere. Also I read that MIT cable was used but was very hard to work with. I was thinking any OFC 10 gauge speaker cable might work. Any ideas? thanks

westmassguy · April 2014

F1nut wrote: »

Yes correction, I meant non-magnetic....thanks Schurkey.

As stated, the primary windings go to one speaker, the secondary windings go to the other.

To keep it as simple as possible in order not to confuse anyone the following works perfectly and there is no reason to change it.

Red/Yellow (right pin) to 1+
Black/Orange (right blade) to 1-
Grey/Brown (left pin) to 1+
Blue/Violet (left blade) to 1-

stogie, put a magnet to the hardware. If it sticks to any of it you don't want to use it.

So in essence, it shouldn't matter left vs right, and long as the internal wiring is correct? It's a one to one isolation transformer, it should be bi-directional.

Schurkey · April 2014

westmassguy wrote: »

So in essence, it shouldn't matter left vs right, and long as the internal wiring is correct? It's a one to one isolation transformer, it should be bi-directional.

You could connect either the left or the right channel to the primary windings, and the other channel to the secondary windings. You will have to keep the color-coded wire pairs of the transformer correct, and you will have to pay attention to + and -.

The transformers are NOT 1:1, but they're close to 1:1. I'm thinking that the primary wire gauge is different from the secondary wire gauge. That's the basis for my comment about the transformers being asymmetric, which has to screw with the SDA signal, although perhaps inaudibly.

If I were running a group-buy of transformers, I'd tell the manufacturer that I wanted the primary and secondary windings to be identical--same wire size, same number of turns. That's NOT how the typical "isolation transformer" is built, so it'd be a custom-job.

westmassguy · April 2014

Schurkey wrote: »

You could connect either the left or the right channel to the primary windings, and the other channel to the secondary windings. You will have to keep the color-coded wire pairs of the transformer correct, and you will have to pay attention to + and -.

The transformers are NOT 1:1, but they're close to 1:1. I'm thinking that the primary wire gauge is different from the secondary wire gauge. That's the basis for my comment about the transformers being asymmetric, which has to screw with the SDA signal, although perhaps inaudibly.

If I were running a group-buy of transformers, I'd tell the manufacturer that I wanted the primary and secondary windings to be identical--same wire size, same number of turns. That's NOT how the typical "isolation transformer" is built, so it'd be a custom-job.

Schurkey, I understand what you're saying. I've always heard them referred to as one to one. Any difference must be inaudible though, with all the critical listeners we have here. If it weren't we'd have heard about by now.

F1nut · April 2014

For the 1000VA tranny the primary is 18AWG and the secondary is 16AWG, both rated at 115V and 4.35A. I don't know the AWG for the 800VA tranny, but it is also rated at 115V both and 3.48A. They are sold as 1:1 trannies. It's entirely possible that more 18AWG is used to balance out the sides. Regardless, no one has been able to hear any imbalance. Speaking for myself, if there was one I am 100% confident I would notice it.

DarqueKnight · April 2014

Schurkey wrote: »

Agreed. I had hoped to goad DK into using his Magic Scope to analyze the electrical imbalance of these "isolation transformers" but he didn't take the bait like I expected.

You also asked this question in this thread from 2012 (posts 167-174):

The-AI-1-Dreadnought-Project-Pt.2-Upgrade-to-1000VA-Transformer

This subject was first addressed in posts 62-71 of this thread:

The-AI-1-Dreadnought-Project-Pt.1

When I measured the left and right stereo and dimensional outputs of the Y236906 800VA transformer in 2008, there was a few percent difference in the outputs of each direction, but it certainly could not be considered as an "imbalance".

DarqueKnight wrote: »

In terms of dB, the differences in voltage amplitudes between channels are:

60 Hz

0.12 dB stereo, 0.26 dB dimensional.

1000 Hz

0.38 dB stereo, 0.39 dB dimensional.

With all of the things going on in a stereo sound field, it is not difficult for me to accept that most people would not notice a difference of 0.1 dB to 0.4 dB difference in sound level between channels.

Schurkey wrote: »

These transformers are all intended to accept 115 or 230 volts input on the primary windings, and to provide 115 or 230 volts output on the secondary side. Since all transformers have some amount of "loss", the manufacturer compensates by adding some extra winding to the secondary windings, so the losses of the transformer don't show up as reduced voltage on the secondary windings. We Polkies are using the transformers for an entirely different purpose, we're transferring power BOTH directions--from primary to secondary, but also from secondary to primary. Since the transformer isn't symmetrical, what works to prevent voltage loss in one direction makes the voltage loss worse in the other direction.

Consider that any isolation transformer, even the one used with the original AI-1, will have a small difference in output when comparing primary to secondary direction and secondary to primary direction. This is unavoidable since a 1:1 isolation transformer must include a small step up function to account for transformer losses. It is unavoidable that a signal going in the secondary to primary direction will see a small step down function. However, the output differences between directions should be (and are) inaudible and should be (and are) within the range you would expect from differences in amp channels and differences in loudspeaker drivers and crossover components. The difference between the outputs of each direction will also vary with frequency. The SDA circuit operates from 1600 Hz down.

Schurkey wrote: »

But since I haven't actually built one, and I don't have the Electrical Engineering background (or the 'scope) to run tests, I am just making guesses that the SDA signal is compromised.

No, the SDA signal is not compromised.

Schurkey wrote: »

Yes, nobody who's using one of these is complaining of SDA signal imbalance. Maybe that's good enough.

No, no one using either a Dreadnought or the original AI-1 has complained of an SDA signal imbalance because there was none.

I will make a separate thread on the topic of AI-1 transformer output ratios so that it will be easy to find.

DarqueKnight · April 2014

F1nut wrote: »

I don't know the AWG for the 800VA tranny, but it is also rated at 115V both and 3.48A. They are sold as 1:1 trannies.

The Avel Lindberg Y236906 800VA isolation transformer uses 18 AWG wire in the primary and secondary. There is more wire in the secondary.

dpowell · August 2014

Can someone provide a link to where the large SS fender washer can be purchased? Also, I'm interested to know what blade connectors were used for attaching the wires to the Neutrik plugs.

westmassguy · August 2014

dpowell wrote: »

Can someone provide a link to where the large SS fender washer can be purchased? Also, I'm interested to know what blade connectors were used for attaching the wires to the Neutrik plugs.

3/16" female spades

F1nut · August 2014

dpowell wrote: »

Can someone provide a link to where the large SS fender washer can be purchased? Also, I'm interested to know what blade connectors were used for attaching the wires to the Neutrik plugs.

Like I said, I can't remember where I bought mine, but a quick Google search, http://www.boltdepot.com/Fender_washers_Stainless_steel_18-8.aspx?nv=l

Pretty sure the hole in the tranny will take a 3/8" bolt, so you want a 3/8 fender washer. 1 1/4" diameter should work. Also, check Lowes I think they have them as well.

I used #10 female spades from the local hardware store.

nspindel · August 2014

Glad to see this thread pop up, I'm going to link to it on the group buy page.

dhlogic · August 2014

I have a few questions to help me understand why this transformer is wired the way it is.

In a normal power supply application I understand having dual primaries and secondaries as it gives you options on whatever input you have (120 vs 240) and on the output if you want the secondaries voltage 2x at the same current if wired in series or secondaries voltage remaining the same with 2x current if wired in parallel.

With a 1:1 transformer with dual primaries and secondaries as long as both are wired the same, in series or parallel, there's no real "transforming" going on right? So why pick one over the other?

Transformers also typically have a dot marking leads for polarity purposes. On Avel Lindberg I see that the blue and violet on the primary and black and orange of the secondary are marked. In the quote above it mentions connecting the primary's blue and violet to the negative and grey and brown to the positive and done in the same manner on the secondary side, the black and orange to the negative and red and yellow to the positive.

Now this is kinda "backwards" in going along with the dot notation on the transformer, but because this is 1:1 and both primary and secondary are wired the same way, whether they are to the positive or negative speaker terminal is just semantics right?

dpowell · August 2014

F1nut wrote: »

Like I said, I can't remember where I bought mine, but a quick Google search, http://www.boltdepot.com/Fender_washers_Stainless_steel_18-8.aspx?nv=l

OK that helps because I wasn't sure if I was looking for audio-grade spade connectors or just whatever was available. Also, it appears from other pictures that the fender washer being used is contoured in the middle rather than flat. I saw the boltdepot website when searching but didn't see a washer like I was seeing in other post pictures.

F1nut · August 2014

You can't use a contoured washer with the 1000VA as the center is potted unlike the 800VA. Flat fender washer only.

Toolfan66 · August 2014

Doug,

I didn't order anything special, I just went to the hardware store and found an aluminum bolt, and flat washers, and I did add a lock washer. The contour washer is not necessary, just use a stainless or aluminum bolt, and washers..

The one thing I see no one talking about is Dynamat, I would, and I do is Dynamat the inside of the case..

Dreadnought Assembly Questions

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